LAUREL -- When a Maryland apprentice rider flourishes, it's hardly news. But when the best ranking for a bug boy is 10th in the Laurel Race Course standings, that's a different story.

Shawn Payton, one of six bug boys to campaign regularly at Laurel this meeting, is the only one in the top 10. He's 10th with 24 winners; the leader, Mike Luzzi, has 82.

can't remember the last time it was like this," said longtime jockeys' agent Pat Flynn, who books mounts for apprentice Calixto Juarez.

With Mark Johnston, now a journeyman, poised to become the 1990 Eclipse Award winner for top apprentice -- and latest of seven Maryland-based bug champions -- racing people are wondering this about apprentices in Maryland: What have they done for us lately?

"Let's face it," said trainer King Leatherbury, who is not averse tusing bug riders, "but these guys have some very big shoes to fill. You've had guys like [Kent] Desormeaux and Mark Johnston dominate in recent years.

"What they've shown us is that they're not measuring up tthose other guys, and that's really no knock on this current crop. Many of the top outfits have given them the chance to be there [among the leading riders], but it hasn't happened yet."

AFlynn, like many observers, says there are additional reasons for a slowdown. They are:

A talented, veteran riding colony. Of the top seven jockeys, six were not Maryland regulars as recently as two years ago.

A rule instituted last summer that banished the system giving an apprentice a 10-pound allowance until he won his fifth race and a 7-pound allowance until he won his 35th. Now, a bug boy gets a 5-pound allowance from the outset of his apprenticeship.

A rule that does not allow an agent to give more than two "calls" (commitments to trainers in a given race), which can restrict opportunities in high-filling races, such as maiden events.

The pinnacle of using the bug came when Desormeaux was here [in 1987]," Leatherbury said. "It kept up while others were able to follow him well enough, so it was bound to stop some time."

The 5-year-old mare, trained by Jim Murphy, had not won since Oct. 7, 1988. "I'm glad for everybody who works with her," winning rider Donnie Miller said. "I've been riding her since she was a 2-year-old and we had high hopes for her, but she never seemed to pan out."

Miss Rusty defeated Sith Najibe, trained by Leatherbury, by a neck. Leatherbury had two winners on the program, both ridden by Johnston, who won three overall.

* Leatherbury said Thirty Eight Go Go "has checked out fineafter pulling up badly at the end of the All Brandy Handicap on Saturday, and will run again.